In this work, CdTe quantum dots (QDs) were controllably grown onto the surface of layered double hydroxide (LDH) aiming to develop a sensitive and selective method for the electrochemical detection of ciprofloxacin (CPX). Emission and absorption spectroscopy results as well as high-resolution transmission electron microscopy (HRTEM) images evidenced the formation of LDH/QD hybrid material. Unmodified carbon paste electrodes (CPE) as well as CPE chemically modified (MCPE) with native LDH and with the LDH/QD hybrid were prepared for CPX detection, revealing that MCPE-LDH/QD had the highest sensitivity for the detection of ciprofloxacin. Optimum detection conditions included a modifier dosage of 20% in MCPE, Britton-Robinson (BR) buffer (pH 6.0) as analytical medium, 300 s accumulation time and a scanning rate of 20 mV s-1. Linear current versus concentration curve was observed from 2.5 × 10-8-1.2 × 10-5 mol L-1 (coefficient of determination (R2) = 0.995), with sensitivity (limit of detection (LOD) = 4.2 × 10-8 mol L-1; limit of quantification (LOQ) = 1.3 × 10-7 mol L-1), precision (relative standard deviation (RSD) = 3.0%), accuracy (94.0%) and satisfactory selectivity in the presence of Zn2+, Fe2+, Cu2+, citric acid and ascorbic acid. Tests of CPX determination in commercial 500 mg ciprofloxacin tablets evidenced the applicability of the method.
Keywords:
CdTe; semiconductor nanocrystals; hydrotalcite; ciprofloxacin; cyclic voltammetry
